1. Field of the Invention
The present invention relates generally to analytical instruments, and more specifically to an ionization source for electrospray ionization mass spectrometry and its MS analysis.
2. Description of the Related Art
Electrospray Ionization (ESI) is an ionization technology used in mass spectrometry, which was first suggested by Dole et al. (M. Dole, L. L. Mack, R. L. Hines, R. C. Mobley, L. D. Ferguson, M. B. Alice, J. Chem. Phys. 49, 2240, 1968). Thereafter thousands of scientists around the world poured into this field since Nobel laureate John B. Fenn and his group first applied ESI to proteins and other biological macromolecular mass spectrometry in the late 80s, but the ionization mechanism still stays in two models: Ion Evaporation Model (IEM) and Charged Residue Model (CRM). The two theories describe the formation of gas-phase ions singly charged after the droplet left Taylor cone. Under ESI condition, there is a general explanation for the origin of multiply charged ions, which from the surface of the polar droplets may be formed in liquid phase in ESI.